Can an ArticulationBody be joined to a Rigidbody?

I want to use an ArticulationBody tree to simulate an arm, which can grab other objects. Ideally, my "Hand" ArticulationBody would use a joint to connect to the grabbed Rigidbody, but joints can only connect two Rigidbodies. I've tried adding both a Rigidbody and an ArticulationBody to a single GameObject, which surprisingly seems to work, but adding a joint results in random nonsensical behaviour. Am I missing something, or is this completely impossible?